Modeling the asymmetric thermo-mechanical behavior and failure of gray cast irons: An experimental–numerical study with separate Johnson–Cook parameters

Abstract

In this study, the asymmetric (different tensile and compressive behavior) thermo-mechanical behavior and damage of gray cast irons (EN-GJL-200, EN-GJL-250, EN-GJL-300), which are widely used in industrial applications, under different strain rates and temperatures were investigated by a combination of experimental and numerical methods. The mechanical response of the materials was characterized by quasi-static tensile and compression tests at room temperature and elevated temperatures up to 700 °C, Split Hopkinson Compression Bar (SHPB) tests for high strain rates (up to ∼3600 s⁻¹) and tensile tests with specimens of different notch radii to analyze the damage behavior. Based on the experimental data obtained, the Johnson-Cook (JC) material (A, B, n, C, m) and damage (D1-D5) model parameters were calibrated separately for both loading cases in order to capture the apparent asymmetric behavior of gray cast irons under tensile and compression loading. These separate parameter sets were integrated into ANSYS Autodyn finite element software through FORTRAN-based user-defined subroutines and virtual tensile, compression and SHPB tests were performed. Comparing the numerical simulation results with the experimental data, it was observed that the developed asymmetric modeling approach, in particular, represents the thermo-mechanical behavior and damage of the material with high accuracy (deviations in the range of 2–8 % for maximum stress and elongation at break values). This study provides reliable and decoupled JC parameter sets for modeling the asymmetric thermo-mechanical behavior and damage of gray cast irons, allowing more realistic simulations to predict the performance of these materials in demanding engineering applications.